Foot switch for dictating machine

ABSTRACT

A foot-operated control switch having a contact actuating foot pedal which is moved into successive switch positions against a spring force which increases from the first switch position to the next switch position. Because the forces necessary to move the pedal are different for the successive switch positions, the switch positions are precisely defined.

United States Patent Kurt Konrad Guettinger Pfall'hausen, Switzerland757,268 Sept. 4, 1968 Jan. 5, l 971 Dictaphone International AGWettingen, Aargau, Switzerland [32] Priority Sept. 5, 1967 [33]Switzerland 31 No. 12,363/67 [72] Inventor [21 1 Appl. No. [22] Filed[45] Patented [73 Assignee [54] FOOT SWITCH FOR DICTATING MACHINE 12Claims, 5 Drawing Figs.

[52] US. [51 1 Int. [50] Field of Search 200/865 I'l0lh 3/14 ZOO/86.5

[56] References Cited UNITED STATES PATENTS 2,828,379 3/1958 Simonds etal ZOO/86.5 2,95 7,960 10/ l 960 Ginn 200/ 86.5 3,250,874 5/1966 lvinsZOO/86.5 3,432,791 3/1969 Palmer 200/86.5(X)

Primary Examiner-H. 0. Jones Attorney-Curtis, Morris & Safford ABSTRACT:A foot-operated control switch having a contact actuating foot pedalwhich is moved into successive switch positions against a spring forcewhich increases from the first switch position to the next switchposition. Because the forces necessary to move the pedal are differentfor the successive switch positions, the switch positions are preciselydefined.

PATENTEDJAH 5m I 8553405 "SHEETIUFZ INVI'LNI'I'UH. KURT GUETTINGER IIYATTORNEYS PATENTEDJAN SIS}?! SHEET 2 OF 2 INVI'JN'IOR. KURT GUETTINGERIIY ATTORNEYS FOOT SWITCH FOR DICTATING MACHINE The present inventionrelates to a foot-operated control switch for dictating machines and thelike and more particuit is depressed, and even more particularly thisinvention relates to a control switch with a pedal control wherein thepedal is arranged to-oppose a spring force which increases betweensuccessive switch positions.

The object of this invention is to provide a simplified, easily 1operable, dependable dictating machine control switch having a footpedal which can assume successive, yet precisely defined, switchpositions.

In accordance with the teachings, and to accomplish the objectives ofthis invention, a control is provided having a foot pedal, a cam, and afollower member. The follower member of the control is biased againstthe cam, and both the cam and the follower member are arranged forrelative movement with respect to each other. The foot pedal of thecontrol is movably connected to eitherthe cam or to the follower member.

When the foot pedal is not depressed,- that is, when it is in its 1 restposition, the follower member assumes a detent, or catch,

position on the cam. As the foot pedal is depressed, the cam andfollower are caused to leave the detent, or catch, position and to'movewith respect to each other. Adjacent the detent, or catch, positionsection of the cam is a cam section with practically no slope whichcorresponds generally to a first switch positionof the control.Adjoining this slopeless section, is another section with a rising slopewhich corresponds generally to a second switch position. Additional camsections may also be included. These various cam sections make it Inecessary that different pressures be applied to the foot pedal toachieve the various switch positions of the control.

Furthermore, in accordance with the teachings of this invention, areturn spring, whose initial tension can be adjusted, is provided toapply a substantially constant return-to-rest force upon the elements ofthe control throughout the entire switching range.

The invention, as illustrated schematically and in a preferredembodiment will be described in detail below with reference to theaccompanying drawing in which:

FIG. 1 shows schematically the essential parts of a footoperated controlswitch constructed in accordance with this invention;

FIG. 2 is a force curve for the switch illustrated in FIG. 1;

FIG. 3 shows schematically, in cross section, a preferred embodiment ofa foot switch constructed in accordance with this invention and alsoshows arrows representing the forces occurring upon actuation of theswitch;

FIG. 4 shows in top plan view a preferred embodiment of a foot switchconstructed in accordance with this invention with its foot rest removedto better illustrate the parts located beneath the foot rest;

FIG. 5 shows in vertical cross section the foot switch of FIG. 4 withits foot rest in position.

In the foot-operated control switch shown schematically in FIG. 1 a cam,or profile body, 1 is mechanically connected by a lever 2 with a footpedal, or foot rest, 3 of the foot switch so that upon depression of thefoot rest the profile body will be raised. In the example shown the footrest is a plate which is rotatably supported at one end about ahorizontal shaft 4. The other end of the foot-rest plate presses againstone end of the lever 2, shown as force arm 5. The other end of the lever2, load arm 6, is supported in a groove 7 in the base of the profilebody I. The profile body 1 is supported and guided in any suitablemanner so that it can move vertically. The load arm 6, under the actionof a return spring 8, holds the profile body 1 against the bottom plate9 of the foot switch when no pressure is exerted against the foot rest3.

One side surface of the profile body 1 is formed as a cam surface, orslide surface, 10 fora follower member. This follower member, in theembodiment shown, is a leaf spring 11 bent in the shape of a C. Thelower arm of the spring 11 is fastened to the bottom plate 9. The upperarm of the spring II has an end 12 bent in the shape of a circular arc.This curved spring end 12 serves as a follower member. Upon the upwardor downward movement of the profile body, the spring end 12 slides onthe cam surface, or slide surface, 10. The shape of the cam causestensioning of the leaf spring 11 to a greater or lesser extent. Theother side surface of the profile body I, opposite the slide surface 10,has projections I3. Near the projections 13 two pairs of contacts 14 and15 are located one above the other. These contact pairs are actuated insuccession upon an upward stroke of the profile body.

The cam surface 10, consists of three surface sections. namely an uppersection 16, a central section 17, and a lower section 18. The uppersection '16 is formed by a horizontally extending incision in the cam,or profile body, I, which provides a detent, or retaining catch, for thecurved spring end 12 when the profile body 1 and/or the foot rest 3 isin the rest position. The central section 17 consists of a vertical flatsurface, and the lower section 18 consists of an inclined fiat surface.

The transition from the central surface section 17 to the lower surfacesection 18 represents a stop for the end 12 of the spring 11 when theprofile body 1 is moved upward. The two contact pairs 14 and 15, andprojections 13 are so arranged, and/or are of such shape, that when theprofile body is in the rest position, i.e. when the spring end 12 isengaged in the detent or catch position, both contact pairs 14 and 15are open. This position is marked I in FIG. 1. Position II is presentwhen the profile body, or cam, 1 is raised to such an extent that thespring end 12 is at the transition between the central surface section17 and the lower surface section 18. The spring end 12 strikes againstthe stop-presented by the transition between the two surfaces. InPosition II the first contact pair 14 will be actuated, i.e. closed, andthe second contact pair 15 will be opened. In Position III the secondcontact pair 15 is also closed and the Spring end 12 is on the lower camsurface section 18'at a certain distance from the stop point betweensections 17 and 18. This Position III can be fixed by a stop (not shownin FIG. 1) which limits the stroke of the profile body.

The force of the return spring 8 and of the leaf spring 11 (or followermember, 12, due to the leaf spring 11) must be overcome, upon actuationof the foot switch, by pressure on the foot rest 3. FIG. 2 shows a curveof the force required for the foot switch. Only the essential variationsin pressure or force with respect to the displacement of the foot restor profile body are shown.

The return spring 8 is of such spring characteristics and is arranged insuch a way, as will be described in detail below, that the return forcepresent by spring 8 remains practically constant throughout the entireswitch range of the foot switch, i.e. for the lifting of the profilebody 1 out of Position I through Position II and into Position III. Inorder to overcome the return force of the return spring 8, a force F2 isrequired which is shown in the Force-Path diagram of FIG. 2 by a lineparallel to the abscissa. The tension F1 of the spring 11 is dependenton the path of the cam 10.

In the rest position the spring 11 is engaged with a certain pressure inthe detent position 16 of the profile body I. To disengage the spring 11a corresponding force is required which is transmitted from the upwardpressed profile body to the curved spring end 12. Accordingly, thelifting of the profile body begins only when the pressure on the forcearm 5 of the lever 2 has become great enough to disengage spring end 12.Accordingly, the required-force curve has, for Position l, a verticallyextending branch which is composed of the section a, the force necessaryto overcome the return force of the spring 8, and the section b, theforce required to disengage the spring 11 from the detent position.

Upon the lifting of the profile body I out of Position I into PositionII, the spring end 12 slides on the vertical cam section 17. In order tolift the profile body this distance it is necessary, in addition tosupplying the force F2, to supply a force necessary to overcome thefriction between spring end [2 and lowing branch b.

The end of the branch corresponds to the Position ll ofthe profile bodyin the diagram, i.e. the position in which thespring end 12 comesagainst the stop formed by the cam surface section 18 at its junctionpoint with cam surface section: 17. In order to overcome this stop it isnecessary to apply a. certain additional force, indicated in the diagramas vertical branch d. The slope of the cam surface 18 of the profilebody 1 is selected so that the force required to overcome this stop isgreater than the force for disengaging the spring end 12 from the detentposition. This is readily possible since the spring has a greatertension in Position II than in position I.

Upon further rise of the profile body 1 out of position 11 into PositionIII the spring end 12 slides on the cam section 18, whereby the spring11 is subject to further tension. Corresponding to this movement of theprofile body 1, a rising straight line results in the Force-Path diagramas a branch of V the force curve. The end of this branch of the curvedesignates,

Position III of the profile body. I

The force F3 which is necessary toactuate the switch and i which acts onthe force arm 5 of the lever 2 is provided, in the case of a footresting on the foot rest 3, by the weight'of the foot and by anadditional applied pressure. The portion of the force supplied by theweight of the foot is indicated in the diagram of FIG. 2 by a line F3,parallel to the abscissa. The initial tension of the return spring 8 isadjusted in such a manner that this parallel line F3 in the diagramintersects the branch c of the curve, preferably at the center C betweenits end points A and B; The pressure F3 which must be applied inaddition to the weight of the foot in order to actuate the foot switchis represented by all sections of the curve which lie above this DA doesthe profile body 1 rise and drop" out of the rest. position (Position I)into the first switch position (Position II) 1 in which position thepair of contacts 14 is closed. The force required in Position II isindicated by the Point B on the curve. Point B lies below the parallelline F3,. Accordingly, in order to hold the switch in the first switchposition, (i.e. in Position- II), the weight of the foot is sufficientby itself. For the actuating of the second pair of contacts 15 theprofile body must be lifted from Position ll into Position Ill. Toeffect this, the pressure required on the foot rest is greater than thatrequired to lift the profile body into Position II. Thus, this positionll, i.e.

the'switch position most frequently used in operation, is stable and cannot, for all practical purposes, be passed by unnoticed.

The combination described above of a path-dependent:

operating force, corresponding to the diagram of FIG. 2, and a constantreturn force which can be adapted to the weight of the foot, assures forthe easy, energy-saving, dependable actuation of the foot switch.

A preferred embodiment of such a foot switch is shown in FIGS. 3, 4, and5. FIG. 3 schematically shows the construction. of this switch. As canbe seen, the switch has two similar sec tions which are symmetricalabout a vertical center line. Each section is formed essentially in thesame way as the switch shown in FIG. 1. The profile body 19,accordingly, is provided with slide surfaces 20. and 21 on each of twoopposite sides.

' Each slide surface is shaped in exactly the same manner as theFurthermore, the profile body l9-isprovided'withgrooveszfl. and 26 cutrespectively on two opposite sides-of the profile body 19. The endsof'the load arms 27"and 28 of the two levers 29 and 30areengaged in thegrooves 25 and 26. For ease of-il lustration, the grooves 25' and 26have been shown atthe top of the profile body, while in the-actualembodiment they are located in the base of the profile body FIG. L'Thelevers 29 and30'aredouble-arm levers. hosepiyotpoints 31 and 32 aresupported on the base plate of 00 witch. The foot rest'33 is in theformof a hollow sphe a gment and rests on the force arms 34 and'35of the twoley The return spring is a leaf spring 36 which-is supported on the loadarms 27 and 28-of the levers; Each supportpoint-ST and 38 ,lies in Q thevicinity of, apivot point'31 and 32' which is preferably spaced from thelatter by-a distance which corresponds to the length of the force arm.In the center of the leaf spring is a tensioning device by which theinitial tension F of the springcan be, adjusted. lnthis embodiment, asmall spring path is obtained overtheentire stroke of the profile bodyso that, even. with the relatively large length of'spring', th'e returnforce is' substantially constant throughout the entireswitch range.- The4'and 5; In the plan view of FIG. 4-the"foo"t 'rest has been omitted inorder to more readily show the parts'locatedb'elow the foot rest. Theindividual parts are mounted o'n'a circular plate -41.which is providedwith a rubber covering 42 on its underside. so that'the switch will beprevented from sliding on polished floors. Both levers 29 and 3.0areT-shaped with rela tively wide crossarms and are formed of sufficientlythick plate material. They are arranged on the base plate 41 sothattheir feet'come together in the center of the plate and rest ingrooves located in the profile body 19. Each lever is turnable,

orrotatable, about the center line of the crossarm by which it'- issupported. For example, levers 29 and 30 are rotatable. at the ends ofthe arm about pivot points 43 and 44 respectively. The longitudinaledges of the cross arm are bent obliquelyupward- The profile-body 19 isarranged to slide on a vertical' center pin 45 and the curved ends23'and24 of the U shape leaf spring 22 "rest with a certain pressure'on theslide surfaces 20 and 2110f the profile body (see FIG. 3). The returnspring 36'rests at its two ends on the upward bent inner edges 46 and:47 of the lever crossarms. The center of the return spring is action onthe ring 49.- To support the foot rest 33 a leaf springr 50 can suitablybe'employed as shown. This leaf spring is held: on'both ends by two staybolts 51 fastened to the baseplate 41. The center of this leaf spring isscrewed from the outside to the center point of the foot rest.

Switch contacts 39 and 40 are actuated byoperation of either of thelevers 29 and 30. The operation of the foot switch shown in FIGS; 4 and5 corresponds entirely to the operationof the foot switch described inconnection with FIG. 3. By turning the head 55 of the set screw 48,-which.is counter sunkin-the bottom of the foot switch, the initialtension of thereturn spring 36 is adapted, as previously described, tothe weight of thefoot. In setting the screw 48 only the portion of theweight of the foot resting on the foot rest, rather than the entireweight of the foot, need be taken into consideration. By trial and errorthe correct adjustment can rapidly be determined. a

When operating the foot switch it is immaterial at what point the footrest against the foot rest or at what point the foot depresses the rest.For all points of foot contact on the 'rest the switching propertiesdescribed are retained. A light pressure exerted for a short time bringsthe switch into its first switch position and a stronger pressure bringsthe switch into its second switch position. In the second switchposition the dictating machine is caused to backspace.

It should be understood, of course, that the foregoing disclosurerelates only to a preferred embodiment of the invention and thatnumerous modifications or alterations may be made therein withoutdeparting from the spirit and the scope of the invention as set forth inthe appended claims.

Iclairn:

l. A foot-operated control switch having a foot pedal normally in a restposition and movable from said rest position to at least two respectiveswitch positions wherein normally open switch contacts are caused to beclosed, said foot pedal movably connected to one element of a movablymounted cam and follower and adapted to cause relative movement betweensaid cam and said follower and to move said cam and said follower intodefined positions relative to each other corresponding to said restposition and said switch positions of said foot pedaLsaid cam has aprearranged pattern including a notch and the follower assumes a detentposition in said notch on the cam when the foot pedal is in the restposition and wherein adjoining the detent position on the cam is a camsec- I tion which extends substantially without slope which isimmediately followed by another cam section having a raised slope andwherein saidfoot pedal is maintainable in said two switch positions,said follower biased against said cam and held there by a force whichvaries in accordance with the prearranged pattern as said cam and saidfollower move with respect to each other, said force providing achanging resistance to the relative motion of said cam and said followerand hence providing a changing resistance to the motion of said footpedal, said changing resistance used to indicate said switch position,whereby the switch positions of said footoperated control switch areclearly defined.

2. A foot-operated control switch as described in claim 1 .having anassociated adjustable return spring adapted to supply a substantiallyconstant return force for all positions of said foot pedal.

3. A foot-operated control switch as described in claim 2 wherein saidfoot pedal is connected to said cam, said force biased follower isstationary, and said cam is movable with respect to said follower.

4. A foot-operated control switch as described in claim 3 having aspring and wherein said force is supplied by said spring.

. 5. A foot-operated control switch as described in claim 4 wherein oneend of said spring is said follower.

6. A foot-operated control switch as described in claim 5 having a levermechanism connecting said foot pedal to said cam wherein said levermechanism is also connected to said return spring and wherein saidreturn spring is attached so that larger transmission ratio is presentbetween the foot pedal and the cam than between the cam and. the returnspring.

7. A foot-operated control switch as described in claim 6 wherein thelever mechanism consists of two double arm levers which are arrangedopposite each other and wherein load arm ends of each of said levers ismovably connected to the cam.

8. A foot-operated control switch as described in claim 7 wherein saidlevers have at least 3 points of attack lying on a circular arcadaptable to receive an actuating force and wherein said axes ofrotation of said lever arms are symmetrically spaced with regard to saidare.

9. A foot-operated control switch as described in claim 8 wherein saidfoot pedal is shell shaped and wherein said foot pedal may be depressedat any point along its periphery to actuate at least one of said levers.I

10. A foot-operated control switch as described in clarm 9 wherein thereturn spring is a leaf spring supported on the load ends of the levers,the initial tension of said leaf spring being adjustable.

11. A foot-operated control switch comprising, a foot pedal and a returnspring therefor, a switch actuator having a control surface andoperatively connected to said foot pedal for movement against the biasof said return spring from an initial position to a first switchposition, means spring biased against said control surface andcooperating therewith providing a resistive force to movement of saidfoot pedal whereby the force resulting from the weight of the foot isless than the force required for initially moving said switch actuatorfrom its initial position but greater than the force required to holdthe switch in said first switch position once said second switchposition is obtained.

12. A foot-operated switch control as described in claim ll wherein saidswitch actuator may be moved to a second switch position by increasingthe force required to hold said switch in said first position.

1. A foot-operated control switch having a foot pedal normally in a restposition and movable from said rest position to at least two respectiveswitch positions wherein normally open switch contacts are caused to beclosed, said foot pedal movably connected to one element of a movablymounted cam and follower and adapted to cause relative movement betweensaid cam and said follower and to move said cam and said follower intodefined positions relative to each other corresponding to said restposition and said switch positions of said foot pedal, said cam has aprearranged pattern including a notch and the follower assumes a detentposition in said notch on the cam when the foot pedal is in the restpoSition and wherein adjoining the detent position on the cam is a camsection which extends substantially without slope which is immediatelyfollowed by another cam section having a raised slope and wherein saidfoot pedal is maintainable in said two switch positions, said followerbiased against said cam and held there by a force which varies inaccordance with the prearranged pattern as said cam and said followermove with respect to each other, said force providing a changingresistance to the relative motion of said cam and said follower andhence providing a changing resistance to the motion of said foot pedal,said changing resistance used to indicate said switch position, wherebythe switch positions of said footoperated control switch are clearlydefined.
 2. A foot-operated control switch as described in claim 1having an associated adjustable return spring adapted to supply asubstantially constant return force for all positions of said footpedal.
 3. A foot-operated control switch as described in claim 2 whereinsaid foot pedal is connected to said cam, said force biased follower isstationary, and said cam is movable with respect to said follower.
 4. Afoot-operated control switch as described in claim 3 having a spring andwherein said force is supplied by said spring.
 5. A foot-operatedcontrol switch as described in claim 4 wherein one end of said spring issaid follower.
 6. A foot-operated control switch as described in claim 5having a lever mechanism connecting said foot pedal to said cam whereinsaid lever mechanism is also connected to said return spring and whereinsaid return spring is attached so that larger transmission ratio ispresent between the foot pedal and the cam than between the cam and thereturn spring.
 7. A foot-operated control switch as described in claim 6wherein the lever mechanism consists of two double arm levers which arearranged opposite each other and wherein load arm ends of each of saidlevers is movably connected to the cam.
 8. A foot-operated controlswitch as described in claim 7 wherein said levers have at least 3points of attack lying on a circular arc adaptable to receive anactuating force and wherein said axes of rotation of said lever arms aresymmetrically spaced with regard to said arc.
 9. A foot-operated controlswitch as described in claim 8 wherein said foot pedal is shell shapedand wherein said foot pedal may be depressed at any point along itsperiphery to actuate at least one of said levers.
 10. A foot-operatedcontrol switch as described in claim 9 wherein the return spring is aleaf spring supported on the load ends of the levers, the initialtension of said leaf spring being adjustable.
 11. A foot-operatedcontrol switch comprising, a foot pedal and a return spring therefor, aswitch actuator having a control surface and operatively connected tosaid foot pedal for movement against the bias of said return spring froman initial position to a first switch position, means spring biasedagainst said control surface and cooperating therewith providing aresistive force to movement of said foot pedal whereby the forceresulting from the weight of the foot is less than the force requiredfor initially moving said switch actuator from its initial position butgreater than the force required to hold the switch in said first switchposition once said second switch position is obtained.
 12. Afoot-operated switch control as described in claim 11 wherein saidswitch actuator may be moved to a second switch position by increasingthe force required to hold said switch in said first position.